Getting to Nova Scotia is easy by car, train, ferry, or plane.

There are direct flights to Halifax from London, Paris, Frankfurt, New York, Philadelphia, Boston, Toronto, and Montreal. See www.flyhalifax.com for up-to-date information.

ViaRail has train service into Halifax. 

The CAT high-speed ferry is no longer in service.

Another option for getting to Nova Scotia is The Princess of Acadia ferry from St. John, New Brunswick to Digby, Nova Scotia,   http://www.bayferries.com.  One could also continue to drive north into Nova Scotia from New Brunswick, entering the province at Amherst. The highways through Maine and most of New Brunswick are excellent and often scenic, so this is generally a better option than the ferry, unless you are planning to visit only the far western end of Nova Scotia.